1. Field of the Invention
The present invention relates to transcranial Doppler probe apparatus in general and in particular to an apparatus for selectively placing and fixing a transcranial Doppler probe on a patient's head.
2. Description of the Related Art
Since its introduction in 1982 by Aaslid et al., Noninvasive transcranial doppler ultrasound recording of flow velocity in basal cerebral arteries, J Neurosurgery 1982;57:769-74, the transcranial Doppler (TCD), an ultrasonic device for noninvasively and continuously measuring cerebral blood flow velocity, has been an invaluable research tool for investigators of neurophysiology. While great strides have been made using this technology for both research and clinical monitoring applications, one annoying, if seemingly trivial, mechanical problem has continued to plague users of this device. Vast improvements have been made in transcranial Doppler technology in recent years however there is at present no commercially available method of securing the Doppler probe to the head of the subject which has been consistently satisfactory and reliable.
Presently available methods use the following sequence. First, the investigator locates the Doppler signal by manipulating the probe over the appropriate cranial location. Once having found the signal the investigator attempts to secure the position of the probe using any of a variety of crude fixation methods. For example, tape, Velcro.TM. straps, surgical glue and other items have all been used with varying results. Even experienced users of TCD ultrasonography can at times have difficulty locating the Doppler signal. Once located, translocation or angulation of the probe a fraction of a millimeter in any direction can result in loss or diminution of the signal. Invariably, this is what occurs during the process of securing the probe after location of the signal.